http://hootsuite.com/ is a website I've been using to semi-automate my tweet ads during the day. I say semi, b/c as a free user of the site, I have to go in every day and reassign the day and time for the tweet. There are a couple really nice things about this site I thought I would share today.
1. Yes, I have to reassign the date/time for the post, but it keeps the post from the previously scheduled time.So, I could simply set the day, keep the time and tweet the same, and move on to the next tweet - much easier than copy/paste from a .txt file like I had been before.
2. If you shorten your web address links with their owl.ly shortener, then Hootsuite can give you a summary of how many clicks you get per tweet, per day. You can even use the owl.ly for your website, faceboook, whatever you want and it'll still track the clicks on the link(s).
Something I've been trying to do is vary the times I have the same tweets go out. This way my followers don't have to see the same thing over and over again. Plus, maybe one ad is more effective at a different time than another is.